This program addresses the need for information and guidance on two subjects of importance in the applications of radiation in medicine: (1) analyzing and recommending methods to reduce the risk of potential long-term health effects of ionizing radiation delivered to the body during medical procedures, and (2) the appropriate quantities and units for prescribing, recording and reporting the uses of radiation in diagnostic and therapeutic medical procedures. The applications of radiation for the diagnosis and treatment of disease have increased significantly in recent years, including the rapid growth in use of computed tomography (CT);combined anatomic and physiological imaging involving CT, positron-emission tomography (PET) and fluoroscopy;image-guided cardiology and cancer therapy procedures;conformal and intensity-modulated radiotherapy procedures;and the use of beams of protons and high linear-energy- transfer particles such as carbon ions for the treatment of cancers located in proximity to radiosensitive normal tissue structures. The National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiation Units and Measurements (ICRU) will prepare reports that provide information and guidance on dosimetry and methods of protecting against potential adverse health effects of these radiological procedures in both patients and medical staff. Under this grant NCRP and ICRU will prepare 16 reports that address key issues in the medical applications of radiation, with a focus on providing recommendations related to the safe use of relatively new radiological procedures. During the five-year renewal period for this grant, NCRP will produce six new reports on the following subjects: (A) Basic Cancer Radiobiology (two reports), (B) Diagnostic Medical Imaging (three reports), and (C) Continuous Quality Improvement, Training and Credentialing (one report). ICRU will produce 10 reports, five of which are currently being drafted, in the areas of (A) Radiotherapy Procedures (five reports), (B) Diagnostic Medical Imaging (four reports), and (C) Fundamental Quantities and Units (one report). Relevance to Public Health: Modern medical procedures for diagnosing and treating cancer and other diseases are providing greatly improved methods for the detection and elimination of disease. The purpose of this grant is to provide relevant information and recommendations on the safe use of new diagnostic and therapeutic medical procedures involving exposure to ionizing radiation. The subjects addressed in these reports will aid in the protection of patients and medical staff from potentially adverse effects of radiation, and will assist in the prescribing, recording and reporting of radiation doses used to treat cancer and other human diseases.